Environmental radioactivity intercomparison exercise 2000

The results of the eighth NPL Environmental Radioactivity Intercomparison Exercise are reported. The level of metrological performance observed was generally lower than that observed in the previous exercise. The measurements of both α/β- and β/γ-emitting samples at approximately 2 Bq g-1 per nuclide yielded data which indicated problems with the quantification of Type B uncertainties. The quality of measurements of nuclides used in γ-ray detector calibration was surprisingly low, and there are still problems with measurements of 90Sr and nuclides which exhibit cascade summing. The quality of data for the plutonium nuclides has improved, and usage of traceable standards and reliable nuclear data remains high. (author)